Syrup for soft drinks used in restaurants, bars and the like frequently is marketed in bag-in-box containers from which it is conducted to the point of use through flexible tubing. Wine and other liquids may be dispensed in a similar manner. It is desirable to have a normally closed valve at the container to assure that there is no flow of fluid until the container is connected to the line. Similarly, the line needs to be provided with a shut-off valve to avoid leakage when it is not connected to the container. A unit of this type is disclosed in U.S. Pat. No. 4,564,132. Here the valve attached to the container includes a body with a transverse wall provided with openings, and a bead around the openings. A diaphragm beneath the wall engages the bead preventing flow through these openings. There are openings through the diaphragm outside of where it engages the bead, but in the normal position where the diaphragm engages the bead there is no communication from the diaphragm openings to the opening in the wall.
The other valve unit includes a movable valve member biased toward an end valve seat by a spring. The two valve units are coupled together by means of a rotatable threaded collar which causes the flat end of the valve member to engage a stem that projects from the center of the diaphragm and extends through a central opening in the wall. This is to deflect the diaphragm away from the sealing bead. Also, the flat end of the valve member engages a collar around the pin to cause displacement of the valve member to the opened position.
The disadvantage of this design is that the stem that projects from the diaphragm is not sufficiently rigid when it is made integral with the diaphragm as disclosed for the preferred embodiment in the patent. The diaphragm material must be flexible and when the valve is made in a desirable size the stem has little column strength. Instead of pressing the diaphragm away from the sealing bead, the stem may become bent and fail to move the diaphragm sufficiently. The alternative is to provide a separate stem placed over the end of the diaphragm to extend up through the collar for engagement by the valve member. This also is undesirable because it requires the existence of an additional element in the assembly, raising the cost of construction and the cost of assembly, as well as introducing the possibility of malfunction through improper installation.